Recent advancement in network and diffusion of mobile terminals have made it easy and common for users to enjoy communicating video content or still image content with partners at remote places. For example, there is a service for enabling users to write sentences indicating their tastes, ideas, or the like at any time points on the time axis of an already provided content item. Such communication using the content item is expected to be on the increase with development of display devices and communication techniques.
Patent Literature 1 discloses a technique for generating a video on which comments provided by users are synthesized and distributing the video through the Internet so as to realize such communication.